Field of the Invention
The invention relates to a method for synthesizing polylactide via a living ring-opening polymerization of lactide using organic guanidine as a catalyst and nontoxic organic alcohol as an initiator.
Description of the Related Art
Polylactide (PLA), a synthetic polyester features excellent biodegradability and biocompatibility, have found significant biomedical applications as drug-delivery carriers and so forth. Therefore, it requires that: (1) PLA can be synthesized with the controlled number-average molecular weight (Mn) ranged from 0.5×104 to 5.0×104 for different delivery period; (2) PLA should not contain any toxic heavy metal or organic/inorganic catalyst residue.
Conventionally, the synthesis of PLA employed stannous octoate (SnOct2) as a catalyst. However, the cytotoxicity of SnOct2 has aroused deep concern about the biosafety of materials because, in practice, it is impossible to entirely remove the toxic catalyst residue from the product polymer PLA. In addition, SnOct2 cannot realize the controlled synthesis of PLA via living ring-opening polymerization (ROP).